jsreport is written in node.js and can easily be customized through javascript or run as a part of another node application. See the article jsreport in node.js for the details how to integrate or adapt jsreport.

jsreport-core is lightweight package which contains jsreport main infrastructure but excludes all the extensions. It fits into node.js applications in which you want to use just some particular parts of jsreport and for example exclude the studio web designer. See also post Introducing jsreport-core.

Refer to the article node.js remote client when searching for a way how to remotely communicate with jsreport server through http API.